دانلود رایگان مقاله انگلیسی ترکیب کامپوزیت بتن سبز با خاکستر بادی قدرتمند و چسبندگی شکاف - الزویر 2018

Abstract

Nowadays green buildings are a necessary component of securing sustainability, whereas concrete composites with the addition of siliceous fly ash (FA) can certainly be included in the sustainable and green concrete. Effective promotion of green concrete incorporating FA is required in order to minimize the environment threat due to FA waste disposal and reduce cement consumption. In this paper, effects of FA addition on the compressive strength and fracture toughness of cm f plain concrete are presented. Fracture toughness tests were carried out according to Mode I (tension at bending) following the RILEM Draft Recommendations. The critical values of stress intensity factors, have been determined. S KIc To assess mechanics parameters compressive strength tests and fracture toughness tests were conducted and the results were evaluated comparing with reference concrete. In modified concretes, cement was replaced by FA by its weight. Three test groups were constituted with the replacement percentages as: 0% (FA-00), 20% (FA-20) and 30% (FA-30). During the tests, the effect of age of concretes modified with the additive of FA on analysed parameters was determined. The experiments were carried out after: 3, 7, 28, 90, 180 and 365 days of curing. Based on the obtained results it can be concluded that, it is possible to make green concrete containing FA with high compressive strength and fracture toughness. The properties of composites with the additive of FA depend on the age of the concrete during tests. 20% additive of FA guarantees high and in mature concretes. Moreover results of the and cm f S KIc S KIc the are convergent qualitatively.

 Conclusions and practical tips

On the basis of fracture toughness tests, during Mode I loading, in which a portion of the binder was replaced with active pozzolanic siliceous FA, it can be concluded that: 1. It is possible to make sustainable green concrete with the addition of FA with high compressive strength and fracture toughness. 2. The FA additive in the amount of 20 and 30% of mass of cement significantly affects the change of compressive strength and fracture toughness in tension. 3. Obtained parameter values of and depend on the age of concrete. cm f S KIc 4. FA additive in the amount of up to 30% of mass of cement drastically reduced compressive strength and fracture toughness at early age. 5. 20% FA additive ensures high and in matured concretes. cm f S KIc 6. Concretes with 30% FA additive are characterized by highest dynamic increase of the parameters and . cm f S KIc 7. After 180 and 365 days, compressive strength and fracture toughness of FA-30 concrete is higher in comparison to the values obtained for reference concrete. 8. Results of the fracture toughness and the compressive strength are convergent qualitatively. Green concretes with the siliceous FA additive are used in building structures – both cubature and industrial. Range of composites, made on the basis of the binders modified with this waste is very rich. Such concretes are used in construction industry: concrete, reinforced concrete and prestressed; in structures: monolithic, prefabricated, composite and prestressed. On the basis of the obtained results, several practical tips and recommendations on the use of sustainable concretes, with the siliceous FA, in concrete industry can be suggested: 1. In the case of concretes, which are scheduled for commissioning after 28 days, or later, the preferred solution is to use composites modified with the 20% FA additive.